Hazards - Seismic hazards, Storm hazards, Fires in nature & Case studies Flashcards
what is the primary hazard associated with a seismic event?
-an earthquake = a short period of violent ground-shaking resulting from the sudden release of large amounts of energy in the lithosphere
why do earthquakes occur?
-at all boundaries, plates can become stuck due to friction
-when the plates are stuck, the convection currents in the asthenosphere continue to push, which builds the pressure
-all of this pressure is released in a sudden movement, causing a jolting motion in the plates which is responsible for shockwaves spreading out from the focus
what is meant by the focus?
-the point at which the pressure is released within the crust, i.e. where the earthquake originates from
what is meant by the epicentre?
-the point on the earth’s surface that is directly above the focus, i.e. where the earthquake is felt first
what is the spatial distribution of earthquakes?
-the most powerful earthquakes occur along destructive margins, at depth in the Wadati-Benioff zone, e.g. over 80% of large earthquakes occur along the Circum-Pacific belt ( i.e. the Ring of Fire ), where the Pacific plate is being subducted beneath the surrounding plates
-large, shallow-focus earthquakes are produced at conservative margins, e.g. the San Andreas Fault in California, which represents the boundary between the North American and Pacific plates
-earthquakes at constructive margins tend to be lower magnitude than at destructive or conservative margins
-some minor earthquakes occur away from plate boundaries, e.g. in February 2018, an earthquake of intensity 4.6 on the Mercalli Scale was felt over much of Wales and south-west Britain
how is seismicity measured?
-the Richter scale = a measure of the strength of seismic waves ( i.e. the magnitude of an earthquake ) which doesn’t have an upper limit and is logarithmic, meaning that a magnitude 5 earthquake has an amplitude ten times greater than a magnitude 4 earthquake
-the moment magnitude scale ( MMS ) = a measure of the total amount of energy released at the source of an earthquake which, like the Richter scale, is logarithmic and has no upper limit, however it is more accurate
-the Modified Mercalli Intensity scale ( MMI ) = a measure of the intensity of an earthquake and its impacts using observations of the event ( e.g. reports and photos ) running from 1 to 12, with 1 being an earthquake that is only detected by instruments and 12 being one that causes total destruction, however it is subjective
what is the frequency of earthquakes?
-earthquakes are frequent around the world and hundreds of low magnitude earthquakes that cannot be felt by humans occur every day at boundaries, whereas the larger earthquakes are less frequent
what is the regularity of earthquakes?
-earthquakes don’t seem to follow any clear pattern or trend and are largely random, so there is irregularity between events
what is the predictability of earthquakes?
-scientists can monitor the movement of tectonic plates to predict which areas are at risk from seismic hazards, and microquakes may give some indication
-close studies of fault lines can sometimes indicate the point along the fault where the next earthquake could be due ( i.e. a seismic gap ) because earthquakes push pressure and stress to the surrounding rock, which increases that area’s future earthquake hazard risk
-however, it’s currently not possible to accurately predict when an earthquake will strike a particular place, and what magnitude it’s likely to be as how strong they are is random
what are the three types of seismic waves?
-body waves = P and S, surface waves = love and Rayleigh
-primary / pressure ( P ) waves = longitudinal, fastest, least destructive ( lowest amplitude ), can travel through water, air and solids ( mantle and core )
-secondary ( S ) waves = transverse, medium speed, second most destructive, can only travel through solids ( mantle )
-surface waves = can be longitudinal or transverse, slowest, most destructive
what are the secondary seismic hazards caused by earthquakes?
-landslides and avalanches
-soil liquefaction
-tsunamis
what are landslides and avalanches and why are they hazardous?
-shaking of the ground can dislodge rock, soil or snow, causing landslides or avalanches that move downslope quickly
-shaking can also loosen ground material, making it easier for water to infiltrate, and the weight of the extra water may trigger a landslide even after ground shaking has stopped
-e.g. following the Gorkha earthquake in Nepal in 2015, scientists from NASA found that 4,312 landslides occured between the time of the earthquake in April and the onset of the monsoon rains in June, some of which were large enough to block whole valleys and almost completely bury villages, such as Langtang
what is soil liquefaction and why is it hazardous?
-when violently shaken, soils with a high water content ( i.e. saturated / waterlogged soil ) lose their mechanical strength as particles lose contant with each other, causing the soil to act like a liquid
-this makes the soil weaker and easier to deform, so it’s more likely to subside, and buildings tilt or even collapse as the soil can no longer support its own weight, which causes threat to human life
-e.g. the Palu ( Indonesia ) earthquake of 2018 caused major soil liquefaction within and close to the city of Palu, which led to mudflows that submerged many buildings and a whole village
what are tsunamis and why are they hazardous?
-giant sea waves caused by the displacement of large volumes of water
-generated by shallow-focus underwater earthquakes, volcanic eruptions, underwater debris slides and large landslides into the sea
-around 90% of all tsunamis are generated within the Pacific Basin, particularly at convergent plate boundaries where subduction is taking place
-the waves will wash boats and wooden coastal structures inland, and the backwash may carry them out to sea
-people are drowned or injured by the tsunami as both the water itself and the debris that it contains are hazards
-tsunamis are usually more powerful if they start close to the coast because the waves lose energy as they travel towards land
-the waves travel very fast in deep water so they can hit the shore without much warning, meaning that they can cause a high death toll
-e.g. tsunamis generated by the explosion of the volcano Krakatoa, Indonesia in 1883 have been estimated to have drowned over 35,000 people and produced waves that travelled around the world, the highest being over 40 m
what is the formation of a tsunami?
-tectonic upthrust in the form of underwater earthquakes and ocean floor volcanoes displace large volumes of water in a very short space of time, generating a massive amount of energy
-this energy causes a series of progressive oscillatory waves to propogate over the ocean surface in ever-widening circles at speeds as fast as 500 mph
-as the tsunami waves approach the coastline of a landmass, they are slowed by the friction of their collision with the rising seabed, and their wavelengths become shorted and amplitude increases
-finally, with the wavelength compressed and heightened to large levels ( often between 5 and 10 m ), the giant waves collide with the shore causing massive damage e.g. by uprooting trees and washing away people and property
what is an example of a recent tsunami?
-March 2011, off the Pacific coast of the Tohoku region of Japan
-the most powerful earthquake ever recorded in Japan ( magnitude 9 ) occurred 70 km offshore
-tsunamis generated reached over 40 m in height and in some places penetrated over 10 km inland
-these tsunamis devastated part of Japan’s Pacific coast, causing nearly 16,000 deaths with over 6,000 people injured and 2,500 missing
-over 300,000 people were displaced from their homes
-the built environment suffered with 127,000 buildings destroyed and many more damaged
-people living within 20 km of the Fukushima nuclear power plant were evacuated
-the assessed cost of the damage by insurers was over $30 billion, and the estimated economic cost to Japan was $235 billion
-tsunami waves ran right across the Pacific to North and South America, and in Chile the tsunami created waves 2 m high
what are the social impacts of seismic hazards?
-primary = earthquakes can cause buildings to collapse, killing, injuring and trapping people, and leaving others homeless
-secondary = earthquakes and liquefaction can cause gas and power lines to break which starts fires that kill people, water supplies are contaminated as pipes burst which causes flooding and spreads disease due to lack of clean water, tsunamis can flood large areas which causes death and widespread damage to property
what are the environmental impacts of seismic hazards?
-primary = earthquakes can cause fault lines which destroy the environment, liquefaction
-secondary = earthquakes and tsunamis can damage industrial units e.g. power plants which causes leaks of chemicals or radioactive material that damage the environment, fires can destroy ecosystems, saltwater from tsunamis can flood freshwater ecosystems, killing plants and animals, and salinising water and soil
what are the economic impacts of seismic hazards?
-primary = businesses destroyed through ground-shaking and liquefaction
-secondary = economic decline as businesses are destroyed ( tax breaks etc. ), high cost of rebuilding and insurance payout, sources of income lost, damage to industry may lead to reliance on expensive imports of goods and energy
what are the political impacts of seismic hazards?
-primary = government buildings destroyed
-secondary = political unrest from food, water and energy shortages, borrowing money for international aid and to repair damage puts the country in debt, can be initial choas and lawlessness e.g. looting, money that is earmarked for development may have to be spent on repairing damage rather than on development
how is hazard risk managed?
-preparedness = a state of readiness in preparation for an event
-mitigation = the act of reducing the severity of an event
-prevention = the act of stopping something from happening
-adaptation = the act of changing in order to cope with a new situation
how can the impacts of seismic hazards be reduced through preparedness?
-authorities can install earthquake warning systems which detect weaker seismic waves that may be a sign of a more powerful earthquake to come and tsunami warning systems which send out warnings after an earthquake by TV, radio and SMS, giving people a short time to make themselves safe by e.g. going to evacuation centres or higher ground, e.g. in Japan, the ‘Earthquake Early Warning’ system aims to reduce earthquake-related damage by slowing down trains immediately, controlling lifts and enabling people to protect themselves quickly
-earthquake prone areas such as Japan have extensive awareness strategies and education in place ( e.g. Drop, Cover, Hold On )
-evacuation plans and training so people know how to respond during an earthquake e.g. stay away from buildings if possible or find a strong door frame / desk to shelter under if inside
-within the home, heavy items can be secured and breakable items can be stored at a low level
-families can create a communication plan ( e.g. a groupchat ) and establish an emergency meeting place
-households can create emergency supply kits to last a few days which include essential items e.g. tinned food and water, clothing, a radio, a first-aid kit etc.
-communities can set up search and rescue teams or fire response units to tackle the impacts of a hazard
how can the impacts of seismic hazards be reduced through mitigation?
-older, unsafe buildings can be demolished and replaced with ones specially designed to withstand earthquakes ( i.e. earthquake resistant buildings ) which contain features such as strong materials that can flex and sway but rarely collapse e.g. wood rather than concrete or brick, large rubber shock absorbers in the foundations that will allow some movement without structural failure, cross-bracing to better hold buildings together when they shake and a large concrete weight on top of them that, with the aid of a computer program, will move in the opposite direction to the force of the earthquake to counteract stress
-short-term responses e.g. immediate emergency aid, evacuation, and search and rescue
-regions with a high tsunami risk use warning systems ( such as klaxon ) to warn the population before the wave reaches land, which can reduce loss of life if people react immediately and evacuate, but not loss of property
-some countries have built prevention walls up to 12 m in height to break tsunami waves ( i.e. sea walls ), however these have not proved very effective as large tsunamis are likely to overwhelm them
how can the impacts of seismic hazards be reduced through prevention?
-the majority of seismic hazards cannot be prevented and will occur regardless, however it’s sometimes possible to prevent them from posing a risk to people, e.g. authorities can prevent land that is prone to liquefaction from being built on, or build giant sea walls to prevent tsunamis hitting land
-soil liquefaction can be prevented through soil stabilisation, i.e. gravel columns can be put in the ground
-avalanches can be prevented through controlled explosions
how can the impacts of seismic hazards be reduced through adaptation?
-move away from areas at risk
-capitalise on the opportunities of living in that area e.g. by encouraging tourism
-insurance if living in places at risk to minimise financial loss after an earthquake, thus quicker recovery
-changing lifestyle choices e.g. moving valuable items to a lower level so they cannot fall
-building specially designed earthquake resistant buildings
-building tall, strong buildings which allow people to escape a tsunami quickly and reduce their vulnerability, and buildings with raised, open foundations which are less likely to be damaged
-land-use planning measures which may include putting key buildings ( e.g. schools and hospitals ) in low risk, accessible areas and open spaces ( e.g. parks ) in more high risk areas
-emergency services must adapt their organisation and planning to deal with seismic events, e.g. heavy lifting gear needs to be available and emergency service personnel should be first-aid trained to deal with any casualties following an event before trained medical personnel arrive
what is an example of a recent seismic event?
-the Lombok earthquake is a collective name for a series of seismic events that took place on the island of Lombok in Indonesia between July 29 and August 19, 2018
-Lombok is part of the chain of the Lesser Sunda Islands, along with Bali to the west and Sumbawa to the east
what were the physical causes of the Lombok earthquake?
-Indonesia is a meeting point of several tectonic plates and is one of the most seismically active places on Earth
-it is a typical island arc structure where the Indo-Australian plate is moving northward towards and subducting under the Eurasian plate at an oceanic to continental destructive plate margin
-the Sunda Arc subduction zone is responsible for most of the earthquakes affecting Indonesia including Lombok as friction and sticking between the plates causes immense pressure to build up where the Indo-Australian plate is subducted into the mantle ( the Wadati-Benioff zone ), which is then released as a large earthquake when the plates become unstuck
what were the impacts of the earthquake?
-560 died
-1,600 injured
-445,000 in makeshift shelters
-130,000 houses damaged ( 70% )
-432,000 displaced and living in 2,700 displacement sites
-460 schools damaged
-total cost of US $600 million, which most of was met by the Indonesian government and Indonesian NGOs
what is the response timeline of the 2018 event?
-July 29 = a 6.4 magnitude earthquake strikes off Lombok, the Indonesian Red Cross allocates money from their emergency fund to meet the humanitarian needs of 4,000 people
-July 30 = the local state governor declared a 3-day state of emergency, advice to not return home for fear of aftershocks, assurances made to help rebuild housing and infrastructure in Lombok using the Indonesian armed forces, financial help promised
-August 5 = a 7 magnitude and 15 km deep earthquake, the Indonesian Red Cross launched an emergency appeal for funds to assist 80,000 affected people for 18 months
-August 9 & 18 = a 5.9 & 6.4 magnitude earthquake
-August 26 = the transition process from emergency to recovery phase starts following an announcement by the Indonesian National Board for Disaster Management ( BNPB )
-September = an earthquake hits elsewhere in Indonesia ( Palu ), funds and help are diverted away from Lombok
-November 8 = the emergency appeal asks for further funds to assist 20,000 households for 30 months, including mid to longer-term recovery needs and investment in increased preparedness and resilience
what factors affected vulnerability to the Lombok earthquake?
-building materials = most deaths were caused by collapsing buildings because newer ones are made out of concrete / brick which will easily crack and collapse, and injure people as a result, whereas traditional buildings are made out of timber so they flex and sway but rarely collapse
-level of development = LIC
-tourism = income relies on tourism so buildings had to be rebuilt quickly and at a higher quality than before to stop development decreasing and encourage tourists to visit after the earthquake to aid recovery
what is a tropical storm?
-a low pressure, spinning storm with high winds and torrential rain
what conditions are required for a tropical storm to develop?
-temperature = ocean temperatures must be around 26-27°C and at least 50 m deep
-air pressure = in areas of unstable air pressure, usually where areas of high pressure and low pressure meet ( convergence of air ), so that less dense, warm air rises more readily and clouds can form
-wind shear = winds must be present for the swirling motion to form, but not too strong or the storm system will be ripped apart in the early stages
-rotation = tropical storms only form around the equator, no more than 20° but no less than 5° on either side because the Coriolis effect isn’t strong enough to make them spin
-a trigger = a pre-existing thunderstorm, a spot of very high sea surface temperature, an area of low pressure etc.
what is the formation and development of a tropical storm?
-warm, moist air rises from the ocean surface, leaving an area of low pressure below, which causes warm air from surrounding areas of higher pressure to move into this low pressure area and rise too
-when the warm air rises, it cools adiabatically ( by expansion ) and condenses into thunderstorm clouds, releasing latent heat which acts as feedback, fuelling further uplift
-the whole system is spinning due to the Coriolis effect ( anticlockwise in the northern hemisphere and clockwise in the southern hemisphere ) and it initially moves westwards due to the easterly winds in the tropics
-the constant addition of energy from the warm air rising causes the storm to spin faster and generate higher wind speeds, and at 39 mph the storm can be classed as a tropical storm
-the eye of the storm is in the centre, around 30 miles wide and of extremely low pressure ( can be 15% lower pressure than areas outside of the storm ) where cool ( from the higher altitudes ), dry air ( from the moisture being transferred into the system ) descends, causing the weather to be relatively calm and cloud free
-surrounding the eye is the eyewall, the most intense and powerful area of the storm where warm, moist air rapidly rises, with extremely high winds and torrential rain, and when winds reach 74 mph it becomes a hurricane / cyclone / typhoon
-when the storm reaches a coast, the low pressure and strong winds will cause a large amount of sea water to be taken into the system and then released as a high wave called a storm surge
-when it reaches land, it no longer has a supply of energy ( warm, moist air from the sea ) and the eye eventually collapses
what is the spatial distribution of tropical storms?
-they occur between 5° and 20° north and south of the equator, and once generated, they tend to move westwards and are at their most destructive
-11% are hurricanes ( in the Caribbean Sea / Gulf of Mexico )
-1/3 of all storms every year are typhoons ( off southeast Asia )
-8% are cyclones ( in the Arabian Sea / Bay of Bengal )
-20% are willy-willies ( off north-western and north-eastern Australia )
how is storm magnitude measured?
-the Saffir-Simpson scale = a scale of 1 to 5 based on wind speed, with category 1 being the weakest ( winds of 120-150 km/h ) and category 5 being the strongest ( winds over 250 km/h ), which also estimates how much damage a storm of a given magnitude will do, from limited damage at category 1 to catastrophic damage at category 5
-however, in recent years, nearly 90% of tropical storm deaths in the US were not the result of wind, but water i.e. storm surges, extreme rains and inland flooding
what is the frequency of tropical storms?
-there are around 100 per year, so they are quite frequent
-tropical storms are more frequent in the northern hemisphere between June and November, and in the southern hemisphere between November and April
-the majority of tropical storms don’t develop into strong storms and never reach land, so they never develop into a major hazard
what is the regularity of tropical storms?
-tropical storms are irregular because although they occur in the same areas, their path doesn’t follow a set route as it is dependent on the storm and the climatic conditions, so the hazards created by storms follow no clear spatial or temporal pattern
what is the predictability of tropical storms?
-tropical storms form away from land, so certain cloud formations in tropical areas can be identified from satellite imagery and used to tell when a tropical storm is forming
-the storm can then be tracked using satellite imagery and models, and the general route can be predicted, helping scientists to work out when and where it is likely to hit land
-the path of a tropical storm can therefore be predicted fairly accurately, and the closer it gets, the easier it is to predict
-storm surges can also be predicted based on the pressure and intensity of the storm
what are the predicted impacts of climate change on tropical storms by 2100?
-an increase of 2-11% in the average intensity of storms
-a decrease of 6-34% in the total number of tropical storms
-a substantial increase in the frequency of the most intense storms
-an increase in the number of slow-moving storms because the speed of the winds between the poles and the tropics reduces as polar areas get warmer and there is increasingly less difference in the atmospheric pressure between the two areas, which means they will produce more rainfall, there will be more time for wind to cause damage, and the damage potential from storm surges will increase as a larger wall of seawater is created in front of slower storms
what are the hazards caused by tropical storms?
-high winds
-storm surges
-heavy rain
-flooding
-landslides
what are high winds and why are they hazardous?
-wind speeds on the ground can reach more than 300 km/h and are therefore very strong
-hurricane winds are strong enough to cause structural damage to buildings ( even collapse ), bring down electricity transmission lines, uproot trees and carry debris ( e.g. cars and trees ) long distances before smashing them into other objects, injuring anyone who comes into contact
what are storm surges and why are they hazardous?
-a large rise in sea level caused by low pressure and high winds, pushing water towards the coast
-they cause the majority of deaths in storms and can have a devastating effect on low-lying coastal areas such as river deltas where the flooding can extend a long way inland, and agricultural areas can suffer for a long time as soil is contaminated by sea water ( salinisation )
what is heavy rain and why is it hazardous?
-as warm moist air rises it cools and condenses, causing torrential rain
-it is not unknown for rainfall to exceed 200-300 mm, bringing about severe flooding, landslides and mudslides
-if there is high relief near the coastal area, rainfall could increase to over 500 mm/day
what is flooding and why is it hazardous?
-heavy downpours can cause river discharge to increase suddenly, causing rivers to overtop their banks and flood the surrounding area, which also sends more floodwater to other places, causing areas outside of the tropical storm’s path to flood
-heavy rain and storm surges can also cause flooding in coastal areas
what are landslides and why are they hazardous?
-water infiltrates soil and rock, making it less stable and increasing the risk of landslides during periods of heavy rainfall, e.g. in tropical storms
what are the social impacts of storm hazards?
-primary = people may drown, or be injured or killed by debris carried by high winds or in flood water, buildings and houses destroyed, electricity cables damaged and supplies cut off
-secondary = people are left homeless, flooding causes sewage overflows which contaminates water, lack of clean water can help diseases spread, damage to agricultural land can cause food shortages
what are the environmental impacts of storm hazards?
-primary = beaches eroded, coastal habitats such as coral reefs are damaged, sand displaced, sediment deposited in aquatic ecosystems may damage fish breeding grounds
-secondary = environments are polluted e.g. by salt water, oil and chemicals spilled from damaged factories, animals displaced from flooding e.g. alligators, landslides can block watercourses so they change course
what are the economic impacts of storm hazards?
-primary = businesses destroyed so they can’t trade, agricultural land damaged which affects commercial farming
-secondary = high cost of rebuilding and insurance payout, economic decline from sources of income lost e.g. farming
what are the political impacts of storm hazards?
-primary = government buildings destroyed
-secondary = pressure for government to do more about global warming, political unrest from food, water and energy shortages, borrowing money for international aid and to repair damage puts the country in debt, money that is earmarked for development may have to be spent on repairing damage rather than on development
how can the impacts of storm hazards be reduced through preparedness?
-data from weather satellites can give a real-time view of the location, track, size and strength of a storm, and specially adapted aircraft and weather balloons can be used to predict the future path and strength of potential storms, so people can be warned to evacuate vulnerable areas
-storm drills can be practised e.g. ‘Project Safeside’ is a hurricane awareness programme for use in schools in Florida
-governments can plan evacuation routes and educate people about how to prepare for a storm e.g. by stockpiling water and food and boarding up windows
-as cyclones tend to follow an erratic path, it is not always possible to give more than 12-18 hours warning, meaning in less developed regions where communications are poor, there is insufficient time for a proper evacuation
-Bangladesh’s ‘Cyclone Preparedness Program’ includes an awareness campaign about cyclone warning signals, an early warning system, the construction of over 4,000 storm shelters to reduce storm related deaths ( 2.1 million people were relocated to storm shelters in 2019 and only 8 died, whereas 300,000 died in 1970 ) but not damage to property, replanting former mangrove forest areas to protect areas just inland, and encouraging people to have emergency packs containing dried food and a portable stove so they can survive in the storm shelters for some time
how can the impacts of storm hazards be reduced through mitigation?
-short-term responses e.g. immediate emergency aid, evacuation, and search and rescue
-strengthening the home through waterproofing all external walls, door barricades, securely fixing down roofs etc.
-clearing lose debris before storms
how can the impacts of storm hazards be reduced through prevention?
-in current climates and weather conditions, tropical storms cannot be avoided, however strategies to mitigate climate change could prevent higher category storms
-a number of prevention techniques have been unsuccessfully considered over the last 80 years, including cooling the ocean with icebergs to reduce evaporation, changing the radiation balance in the storm environment by blowing black soot into the storm, exploding the storm apart with hydrogen bombs and blowing the storm away from land with giant fans
how can the impacts of storm hazards be reduced through adaptation?
-move away from areas at risk
-people in richer, at risk areas are urged to take out insurance to minimise financial loss after a storm, thus quicker recovery
-design buildings to withstand high winds and flood damage, e.g. by using stronger materials such as reinforced concrete
-retrofitting structures so they are wind resistant and safer during an event, which is important in poorer areas as the need for land usually outweighs planning considerations to avoid high-risk areas
-building flood defences such as houses on stilts, sea walls, river levees etc.
-land-use planning to identify the areas at greatest risk, e.g. from storm surges, and to limit certain types of development in such areas
what is an example of a recent tropical storm in a HIC?
-Hurricane Michael, USA in October 2018
-it travelled in a northeasterly direction across the Gulf of Mexico before making landfall on the coast of Florida near Mexico Beach, USA in the early afternoon of October 10 with winds of over 250 km/h
-the hurricane then reduced in strength from a briefly category 5 storm to an extratropical storm as it headed inland to hit parts of Georgia, North and South Carolina, and Virginia before reaching the Atlantic
-it travelled in a curved path due to the Coriolis effect which deflects storms to the right in the northern hemisphere
what were the impacts of the 2018 storm?
-flash flooding turned roads into rivers
-16 died as a direct result of wind, storm surge and rain ( i.e. floods ) across the states of Florida, Virginia, NC and SC, and an additional 43 due to falls during the post-storm clean-up, traffic accidents and medical issues made worse by the hurricane
-Florida = power cuts affected nearly 400,000 electricity customers ( about 4% of the whole state ), $18.4 billion damage; Bay County = more than 45,000 structures damaged and 1,500 destroyed including 2 hospitals, trees uprooted, power lines brought down, roofs ripped off and swept into the air, homes ripped open by fallen trees; town of Mexico Beach = 1,584 / 1,692 buildings damaged and 50% destroyed
-agricultural and forestry losses totalled about $3.87 billion, primarily in Florida and Georgia
-total cost of damage estimated at $25 billion
-at least $6.23 billion in insurance claims in USA
what is the response timeline of the hurricane?
-October 7 = residents advised by governor of Florida to prepare for storm
-October 8 = mandatory evacuation for 3 coastal counties including Bay County, schools closed, mayor of Panama City asked 2/3 of county ( 120,000 ) residents to evacuate
-October 9 = president Donald Trump approves a major disaster declaration request for Florida, giving access to federal resources and money for relief and recovery efforts, plans for evacuation made in Georgia
-as the storm approached = more than 20 million people in 5 states remained under either a hurricane or tropical storm warning, while areas in NC and SC flooded by Florence braced for more rainfall, emergency preparedness organisations, e.g. Direct Relief, provided emergency medical packs to health facilities in the storm’s path
-after the storm = Bay County borrowed more than $250 million to pay for the clean-up, 1,500 national guard personnel activated in Georgia, Trump declared a major disaster in 5 counties on October 11 and authorised funding for 75% of the cost of emergency protective measures and removal of storm debris in Georgia, residents were able to receive grants for house repairs, temporary shelter, loans for uninsured property losses and business loans, the Hurricane Michael Relief Network was established by the Federal Emergency Management Agency ( FEMA ) and several private and non-profit organisations to provide direct relief to affected residents
what factors affected vulnerability to Hurricane Michael?
-resilience = Georgia and North and South Carolina were still recovering from the effects of Hurricane Florence which hit earlier that year, so their quality of life was already lower than that of other states on the southeast coast, meaning they were more vulnerable to this hurricane
-level of development = HIC so mostly economic impacts
-location = coastal areas were more vulnerable to the impacts of storm surges, e.g. flash flooding, than inland areas further away from the coast
what is an example of a recent tropical storm in an LIC?
-Typhoon Haiyan / Yolanda, Philippines in November 2013
-it originated in the western Pacific Ocean on November 2 and by November 6, the system was assessed as a category 5 or super-typhoon with wind speeds reaching over 250 km/h
-on November 8, Haiyan made landfall in the central Philippines where the northern eyewall caused great destruction in the area around Tacloban and wind speeds reached 315 km/h, before continuing westward towards southeast Asia and eventually reaching the north of Vietnam on November 10
what were the impacts of the 2013 storm?
-storm surges of up to 6 m
-300 mm of rainfall fell in under 12 hours
-10,000 died, with bodies still being discovered well into 2019
-1,000 declared missing
-widespread damage to buildings and infrastructure ( American army officer observed “I do not believe there is a single structure that is not destroyed or severely damaged in some way” )
-2 million made homeless and more than 6 million displaced, with at least 20,000 fleeing to the capital ( Manila )
-completely washed away some low-lying areas on the eastern side of Tacloban
-large areas cut off, with communication and power systems destroyed
-major roads blocked by flooding, landslides and fallen trees which made relief work almost impossible
-Tacloban city airport damaged by 5.2 m storm surge but had to be repaired quickly as it became the centre of the international aid operation
-widespread looting reported
-local governments collapsed as so many local officials died during storm
-total cost of damage estimated at $2.9 billion
what were the responses to the typhoon?
-over 1,200 evacuation centres were set up, providing aid in the form of shelter
-the main airport reopened 3 days after the storm and emergency aid arrived
-power was restored in some regions after a week
-1 million food packs and 250,000 litres of water were distributed within 2 weeks
-prompt action by the WHO and other relief agencies ensured that outbreaks of waterborne diseases, e.g. dysentery or cholera, were kept isolated and to a minimum
-immediately after the storm, the UN stated that access remains a key challenge as some areas are still cut off from relief operations ( thus geographic variation ) as roads, airports and bridges were destroyed or covered in wreckage
-the UK government deployed 2 navy ships to the Tacloban area supplying over 200,000 tonnes of aid, while the Americans sent numerous ships and aircraft and over 13,000 service personnel e.g. for search and rescue efforts
-long-term responses have included ‘Building Back Better’ which involves rebuilding more resilient housing and replanting damaged mangrove forests to dissipate the energy of tropical storm surges
-early warning systems have since been implemented e.g. PHILAWARE which uses advanced modelling to provide the information needed to give early warning and aid rapid response
what factors affected vulnerability to Typhoon Haiyan?
-location = Tacloban lies in the centre of the Philippines where tropical storms cross from the Pacific Ocean towards southeast Asia, which makes the region the most affected by and vulnerable to typhoons in the world, the shape of the coastline funnels the storm surges into a much smaller area and concentrates the hazard to the city which increases its intensity and damage potential
-level of development = LIC so mostly social impacts and poor people have to depend on foreign aid and NGOs which often don’t have the resources to cope in such emergencies
-human factors = large scale rural to urban migration to cities such as Tacloban due to people looking for opportunities to work and make money increases the vulnerability of poor migrants as they tend to build low quality houses in overcrowded residential areas so more people and property will be affected by storm events and responses will be less effective due to the high density of people who are unlikely to be able to evacuate quickly and safely, many people have built poorly constructed houses on the flat, low-lying land nearest to the sea which makes them vulnerable to storm surges and flooding, others have built houses on steep hillsides which makes them vulnerable to the high rainfall of typhoons which will cause landslides that can devastate whole communities on slopes where vegetation has been removed
what is a wildfire?
-a large, uncontrolled fire that quickly spreads through vegetation
-a quasi-natural hazard
what is the fire triangle?
-the three elements that need to be present for a fire to ignite and burn
-oxygen = initially provided by prevailing winds and then the rising column of heated air above the fire draws in air from surrounding areas and creates its own continuous supply
-heat source = provided by lightning, volcanic eruptions, the sun, burning cigarettes or campfires, slash-and-burn agriculture and arson
-fuel = any flammable material surrounding a fire e.g. trees, grasses and buildings
what are the three types of wildfires?
-ground fires = burn dry peat ( partially decayed organic matter in wetlands that is high in carbon ) or vegetation beneath the surface e.g. tree roots, 540°C, smouldering ( slow, flameless form of combustion ), long-lived, difficult to put out
-surface fires = burn leaf litter and low-lying vegetation, 900°C, can be low or high intensity, easy to extinguish
-crown fires = burn rapidly through the canopy ( top layer of vegetation ) due to strong winds, 1100°C, most intense and destructive, fast-moving, most difficult to contain
what is the ladder effect?
-when fires spread from the forest floor to the canopy due to ladder fuels, e.g. low-lying tree branches and tall shrubs, which carry the fire upwards to taller vegetation
what conditions favour intense wildfires?
-vegetation type = thick, closely spaced vegetation allows fires to spread quickly and easily, some trees ( e.g. eucalyptus and pine ) contain a lot of flammable oil and so burn very easily and intensely, eucalyptus trees shed strips of their bark which helps fires to spread quickly
-fuel characteristics = fine, dry material ( e.g. long grass, thin twigs ) with low moisture levels catch fire and burn most easily, large amounts of thick vegetation that form a continuous cover will help the fire burn more intensely for longer and spread
-climate and recent weather = wildfires occur in a climate that has sufficient rainfall for vegetation to grow but considerable dry spells and droughts to dry out the fuel so it’s more flammable, strong, dry winds provide more oxygen to help the fire burn and spread burning embers, many climatic events ( e.g. the Santa Ana and Diablo Winds in California ) can make wildfires grow more intense and extend wildfire seasons, El Niño ( warm phase ) is thought to provide warmer, wetter seasons to grow vegetation in California but hotter, drier seasons to create more wildfires in Australia, La Niña ( cold phase ) has the opposite effects i.e. dry seasons in California and wet seasons in Australia
-fire behaviour = wildfires burn in different ways ( i.e. ground, surface and crown fires ), fires can throw out burning debris ( firebrands ) that help it spread / ‘jump’ across rivers and into areas, fires spread quickly on hills as the heat rises
what are the causes of wildfires?
-natural = heatwaves, droughts and dry winds which dry out vegetation, lightning if it occurs without much rain, hot lava and ash produced by volcanic eruptions, large amounts of combustible vegetation ( fuel ) with low moisture levels, El Niño which decreases rainfall in Australia and increases it in California, La Niña which decreases rainfall in California and increases it in Australia, positive Indian Ocean Dipole ( IOD ) which decreases rainfall in parts of Australia
-human = accidents e.g. lit cigarettes, campfires and barbeques which act as a heat source, slash-and-burn ( swidden ) agriculture which involves clearing land by burning vegetation, arson which deliberately starts fires
what are the social impacts of wildfires?
-primary = people may be killed or injured if they don’t evacuate in time, homes destroyed, power lines destroyed, reservoirs damaged, agricultural land damaged
-secondary = homelessness, food shortages, health problems e.g. asthma from smoke inhalation, psychological impacts e.g. ongoing stress and depression due to experiencing fire
what are the environmental impacts of wildfires?
-primary = water and air pollution from smoke and ash, habitats destroyed, species at risk of extinction, toxic gases and particulates released in burning, soils damaged as organic matter removed
-secondary = migration patterns of animals affected, atmospheric CO2 increase which could heighten the greenhouse effect and result in global warming, faster surface runoff in vegetation depleted areas which increases flood risk, some ecosystems rely on wildfires to clear dead vegetation which reduces the risk of larger wildfires, some plant seeds ( e.g. lodgepole pine ) need fire to stimulate germination
what are the economic impacts of wildfires?
-primary = businesses destroyed so they can’t trade, agricultural land damaged which affects commercial farming, huge cost of fighting fires ( firefighters, helicopters, water )
-secondary = high cost of rebuilding and insurance payout, economic decline from sources of income lost e.g. farming, visitors discouraged which reduces income from tourism, planes cancelled
what are the political impacts of wildfires?
-primary = government buildings destroyed
-secondary = pressure for government to do more about global warming due to increased frequency, political unrest from food, water and energy shortages, borrowing money for international aid and to repair damage puts the country in debt, money that is earmarked for development may have to be spent on repairing damage rather than on development, conflict between neighbouring countries due to cross-border air pollution
how can the impacts of wildfires be reduced through preparedness?
-evacuation plans and emergency service training / drills so people know how to respond
-authorities can install warning systems which alert people when there are optimal conditions for wildfires ( e.g. hot, dry, upcoming lightning storms ) so they can evacuate if they wish to and campfire bans can be put in place
-computer modelling has been used to understand and predict fire behaviour, improving education on the nature of wildfires
-thermal infrared satellite imagery shows where wildfires are occuring so people can avoid those areas and evacuation shelters can be made avaliable by authorities
-households can create emergency plans and supplies of food, water and medicine
-communities can set up search and rescue teams or fire response units to tackle the impacts
how can the impacts of wildfires be reduced through mitigation?
-short-term responses e.g. immediate emergency aid, evacuation, and search and rescue
-to immediately mitigate the effects, the fire must be extinguished or diverted, e.g. water and flame retardants are sprayed onto large, often inaccessible areas from the air to slow the pace, however this is costly so firefighters also work on the ground beating out the flames and bulldozing large breaks in the vegetation to prevent the fires jumping in certain directions
-controlled burnings remove flammable materials so that less fuel is avaliable
-encouraging the creation of fire-adapted communities who collaborate to identify their wildfire risk and work collectively to reduce their risk of loss
-building with fire-resistant materials and creating firebreaks ( gaps in trees and vegetation ) around settlements to limit the spread
how can the impacts of wildfires be reduced through prevention?
-the ignition of wildfires can be prevented through education and public awareness
-in areas of risk, campaigns teach people the dangers of leaving fires burning in forest areas through barbeques or discarded cigarettes, e.g. Smokey Bear which is a 70 year old US mascot used to provide information on preventing wildfires
-the spread of wildfires can be prevented through clearing areas between trees and other vegetation ahead of wildfires to create firebreaks
how can the impacts of wildfires be reduced through adaptation?
-move away from areas at risk
-insurance if living in places at risk to minimise financial loss after a wildfire, thus quicker recovery
-homeowners can remove all but scattered trees within 30 ft of structures to create a fire-resistant zone, keep driveways accessible for emergency services e.g. firetrucks, keep fire tools avaliable ( shovel, rake, ladder ) etc. to reduce their personal risk
-with wildfires on the increase, globally people may have to make more eco-conscious decisions to reduce CO2 emissions because if temperatures continue to rise, it may lead to unprecedented changes in wildfire patterns
what is an example of a recent wildfire event?
-the 2019-20 Australian bushfire season / the Black Summer
-it began in Queensland in June 2019 and spread across the entire country but mainly southward along the east coast to the states of New South Wales and Victoria, peaking during December and January
what were the physical causes of the Black Summer?
-2019 was Australia’s driest spring on record with temperatures above average across nearly all of the continent, and there was a record heatwave in the summer with a country average of 40.9°C, which provided optimal conditions for the fires as drier vegetation combusts easier
-these conditions were possibly caused by the El Niño of 2019, which resulted in hotter temperatures and reduced rainfall in Australia as the trade winds which blow from east to west across the Pacific Ocean weakened, pushing less warm water to Australia and so reducing the amount of evaporation, increasing the risk of droughts, heatwaves and fires
-the large amount of forest cover ( i.e. fuel to burn ) across the country, particularly along the east and southwest coasts, is likely to have contributed to the high intensity and distribution of the wildfires as it enables them to spread quickly and become out of control
what were the impacts of the fires?
-more than 20% of Australia’s forests burned
-18.6 million hectares of forest and over 5,900 buildings destroyed by March 2020
-at least 34 people died
-1 billion animals killed and some endangered species may have become extinct, e.g. sea lions, koalas and diverse bird species native to Kangaroo Island in South Australia
-total cost estimated at $70 billion
-smoke travelled around 11,000 km across the South Pacific Ocean to Chile and Argentina
-306 million tonnes of CO2 emitted
-3 air tanker crew and 3 fire fighters died due to fatal crashes during firefighting and incidents caused directly by fire conditions
what were the responses to the wildfires?
-a number of states of emergency were declared across New South Wales, Victoria and the Australian Capital Territory ( which includes the capital city of Canberra in NSW )
-reinforcements from all over Australia were called in to assist fighting the fires and relieve exhausted local fire crews in NSW
-the Australian Defence Force was mobilised to provide manpower and air support to the firefighting effort
-firefighters, supplies and equipment from Canada, New Zealand, Singapore, the USA etc. helped fight the fires, especially in NSW
what is a multi-hazardous environment and an example of one beyond the UK?
-an area where two or more natural hazards occur, and in some cases interact to produce complex disasters
-the Philippines is an example of this, which is an archipelago i.e. group of over 7,600 islands in south-east Asia, and is home to over 100 million people
what hazards are the Philippines vulnerable to and why?
-tectonic hazards ( i.e. volcanic eruptions and earthquakes ) = the subduction of the Philippine Sea plate underneath the Sunda plate ( Eurasian plate ) as part of the Pacific Ring of Fire at an oceanic to continental destructive plate margin forms composite volcanoes and large earthquakes at the Wadati-Benioff zone
-tropical storms = it is located 13° N of the equator where ocean waters are warm enough ( 26-27°C ) and the Coriolis effect is strong, and it is the most exposed country in the world to typhoons as it is situated in an area where they cross from the Pacific towards south-east Asia
-landslides = it is generally mountainous ( home to over 2,700 mountains ) and uplands make up 65% of the country’s land, and these steep slopes are left unprotected due to environmental degradation such as deforestation which leads to rapid runoff and saturated soil
-flooding = El Niño and the monsoon season ( July to October ) increases rainfall
-droughts = La Niña decreases rainfall
what are the impacts of volcanic eruptions in the Philippines?
-Mayon = most active, erupted nearly 50 times in the last 400 years, most destructive event in 1814, last eruption in 2018, noted for its lahars as volcanic ash mixes with heavy rainfall from tropical storms
-Pinatubo = erupted violently in 1991 ( 2nd largest eruption on the planet in the 20th century ), can be deadly as 500,000 people live within 40 km of the volcano, early warnings and evacuations saved at least 5,000 in 1991, gases, ash and steam were hurled into the upper atmosphere where they affected global temperatures for at least 2 years and reduced them by 0.5°C, deadly lahars were produced as the explosion was followed by Typhoon Yunya which brought very heavy rainfall, death toll around 850, 200,000 left homeless
what are the impacts of earthquakes in the Philippines?
-17 earthquakes with a magnitude of at least 6 between 2000 and 2017
-1976 off Mindanao ( 2nd largest island ) = magnitude 7.9, caused tsunamis which hit the western coastline around Moro Gulf, killed up to 8,000
-2013 Bohol = magnitude 7.2, killed over 200, injured 800, damaged nearly 80,000 buildings
what are the impacts of tropical storms in the Philippines?
-around 10 every year
-2013 Typhoon Haiyan = killed 10,000, caused storm surges of up to 6 m, 2 million homeless, cost US $2.9 billion
-2018 Typhoon Mangkhut = strongest typhoon in the Philippines since Haiyan, killed 127, cost US $627 million
how have human qualities and responses allowed people to live in the Philippines?
-individuals and communities increase their own resilience as they often understand the risks of hazards, having experienced them before, and many people prepare for hazards themselves, e.g. by widening rivers near settlements to prevent flooding and stockpiling food
-in the past, funding for dealing with disasters was only avaliable after it occurred, which meant that the response was reactive rather than proactive ( trying to prevent or prepare for future hazards ), and there was widespread emphasis on post-disaster relief and short-term preparedness ( forecasting / evacuation ) rather than on mitigation
-from 2009 onwards, the Philippines’ policy on disasters has changed, and the country is now working to increase large-scale resilience to disasters by adaptation, mitigation and management, e.g. by preventing people building in areas at high risk of disaster ( land-use planning ), adapting new and existing buildings and structures to cope with earthquakes, building embankments to reduce flood risk from tsunamis and typhoons, increasing public awareness of hazards and how to respond to them, and monitoring hazards and developing early warning systems so people in at-risk areas have time to prepare
-the current system tends to be more of a centralised top-down system rather than bottom-up ( community based ) which is necessary to give rise to local initiatives and help the most vulnerable communities cope with the hazards when they occur
-the Philippines National Red Cross have started some bottom-up programmes which aim to reduce the impacts of natural disasters by encouraging people to collaborate in protecting their lives and the resources upon which they depend, e.g. by training local volunteers in disaster management, identifying risk through land-use mapping, cooperating with governmental bodies in order to gain financial support and ensure that the programmes have long-term sustainability, and initiating mitigation measures ( sea walls, clean water supplies, evacuation plans etc. )
what is a local scale example of a place in a hazardous setting?
-Gili Trawangan is the largest island ( 3 km long by 2 km wide ) in the chain of three Gili islands just off the north-west coast of Lombok, Indonesia, and the only one of the three to rise significantly ( 30 m ) above sea level
-the island was left devastated after a magnitude 7 earthquake hit Lombok on August 5, 2018 due to the subduction of the Indo-Australian plate underneath the Eurasian plate at an oceanic to continental destructive plate margin creating large earthquakes at the Wadati-Benioff zone
what is social capital and how does it relate to Gili Trawangan?
-the networks of relationships among people who live and work in a particular society, enabling that society to function effectively
-it allows communities to use their personal connections to collaborate, such as in Gili Trawangan where they were able to utilise social capital to recover from the disaster and sustainably rebuild the tourism industry
what human factors affected the island’s vulnerability to the hazard?
-the main means of transportation are bicycles ( rented by locals to tourists ) and Cidomo ( a small horse-drawn carriage ) as there are no motorised vehicles
-the only links to the mainland are by boat
-the island was originally a stop-off location for fishermen, but in 1971, many coconut plantation workers began building makeshift homes and businesses on the abandoned plantation land after the harvests failed, and then in the 1980s, backpackers started discovering Gili Trawangan and westerners moved to the island where they haphazardly developed tourism ( e.g. by creating cheap hotels and bunkhouses )
-chaotic cycles of building, demolition and then rebuilding since the 1980s due to land disputes has resulted in structurally unsound buildings
-there is no permanent police force or hospital, ambulances etc. though many of the dive centres have first-aid trained staff
what were the impacts of the Lombok earthquake on Gili Trawangan?
-8 died
-30% of buildings destroyed and another 40% damaged
-water and electricity supplies cut off
-horses used to pull the carts were running loose
-reports of looting
-it took days for the military to arrive to make the island secure
-three months after the earthquake, the average number of tourists arriving on the island each day was only around 900, compared to 3,000 prior to it
what were the island’s responses to the earthquake?
-doctors, dive instructors and tourists set up a basic camp with oxygen and medical supplies
-many people camped out overnight as they were too afraid to sleep indoors out of fear of aftershocks
-thousands of panicked tourists left the island the day after the earthquake and headed straight for the international airport, where some slept on the floor as they waited for a flight out
-the Indonesian National Agency for Disaster Management responded slowly and complaints were made that, despite the risk of earthquakes, there had not been any disaster mitigation training from the central government
-the Indonesian Financial Services Authority reduced electricity and water bills, and helped businesses secure bank loans
-by February 2019, around 50% of the 500 hotels and restaurants had returned to normal operations
-in September 2019, the government announced that the island was making a rapid recovery, the Cidomo needed to be retained and better organised, the Ministry of Public Works would implement road improvements with work starting on paving the roads from November 2019, a new rubbish management system would be introduced to keep the island clean, and that the jetty would be given priority and rebuilt to meet international standards so that it could better meet the needs of tourists
